Process for producing fireproof viscose

Abstract

The flame retardant viscose is obtained by adding silica to the viscose and subsequently fixing the silica to the fiber, such that the final flame retardant fiber will have regenerated cellulose and a silica polymer providing the fibers with flame retardant properties. Conventionally, the regeneration of the viscose mixture is carried out using zinc sulphate, while the final phase of washing of the fiber is accomplished using sulphuric acid. Both zinc and sulphuric acid are highly contaminating products from the environmental point of view. The invention consists, on the one hand, of replacing the zinc sulphate with aluminum sulphate and, on the other, of replacing the sulphuric acid with hydrogen peroxide or oxygenated water, this minimizing the contaminating effect of the process to an extraordinary extent.

1. A process for manufacturing flame retardant viscose by adding silica to a viscose and subsequently fixing said silica to a fibre, said process consisting of a first phase in which said silica is prepared, a second phase of proportioning of said silica and an addition of said silica to a mass viscose, a third phase of regeneration of the viscose mixture, the fixing of a polysilica acid and finally a phase of washing of the fibre, characterized by the fact that during said third phase of regeneration of the viscose mixture, in which said viscose is coagulated in a spinning bath, zinc sulphate (SO 4 Zn) in said spinning bath is replaced with aluminum sulphate (Al 2 (SO 4 )3), while in said phase of washing of the fibre, said washing is performed through the use of hydrogen peroxide or oxygenated water (H 2 O 2 ) after a phase of bleaching with sodium hypochlorite (NaOCl). 
     
     
       2. Process for the manufacturing of flame retardant viscose, in accordance with  claim 1 , further characterized in that said phase of washing of the fibre is performed in a bath with a concentration of said oxygenated water of 8 gr/l at a temperature of around 50° C. for some 5 minutes. 
     
     
       3. A process for manufacturing flame retardant viscose, comprising the steps of:
 A) preparing said silica in a first phase; 
 B) proportioning and adding said silica to a mass viscose in a second phase to create a viscose mixture; 
 C) regeneration of said viscose mixture in a third phase; 
 D) fixing of a polysilica acid in a fourth phase to create a fibre; and 
 E) washing said fibre in a fifth phase; during said third phase, said viscose is coagulated in a spinning bath, whereby zinc sulphate (SO 4 Zn) is replaced with aluminum sulphate (Al 2 (SO 4 )3), and during said fifth phase, said washing is performed with hydrogen peroxide or oxygenated water (H 2 O 2 ) after a phase of bleaching with sodium hypochlorite (NaOCl). 
 
     
     
       4. The process for manufacturing flame retardant viscose set forth in  claim 3 , further characterized in that said washing of said fibre is performed with a concentration of said oxygenated water of 8 gr/l at a temperature of approximately 50° C. for approximately 5 minutes.